Flame-Retardant 3D Covalent Organic Framework for High-Performance Symmetric Supercapacitors
Madan R. Biradar, Chepuri R.K. Rao, Sidhanath V. Bhosale, Sheshanath V. Bhosale
Abstract
The development of safe supercapacitor (SC) devices has always been a market demand. The design and fabrication of nonflammable electrodes with lower side effects exhibiting high SC efficiency are the ultimate solution. Tris(4-formylphenyl) phosphate (P) and 2,6-diamino pyridine (Py) have been utilized to prepare a three-dimensional (3D) covalent organic framework (COF), named as PFM-COF1. The phosphonate-rich subunit was incorporated to impart flame retardancy properties for use as a potential electrode for safer SC devices. The PFM-COF1 material was fully characterized using solid-state 13 C NMR, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and powder X-ray diffraction (XRD) techniques. The nonflammable PFM-COF1 was employed for the construction of three-electrode and symmetric (S) two-electrode SC devices and exhibited a specific capacitance ( C sp ) of 394.28 and 158 F g –1 at 0.5 A g –1 current density. Moreover, PFM-COF1 displayed a high energy density of about 28.44 Wh kg –1 with a power density of 1077.72 W kg –1 at 0.5 A g –1 . For 2000 cycles, 81% capacitance retention was observed.